1. Field of the Invention
The present invention relates generally to motor vehicles and to apparatus for increasing fuel efficiency, and specifically to an air drag reducing tail gate for a pick-up truck, trailer or the like.
2. Description of the Prior Art
It is believed that relevant art may appear in class 180, in class 280, and in subclass 50 and later subclasses of class 296.
Tail gates are well known in the art. When used on a vehicle such as the pick-up truck shown in U.S. Pat. No. 3,734,560, a tail gate is normally a substantially flat rectangular piece of metal forming the rear wall of a utility or cargo compartment. It normally has at least one solid surface for retaining objects within the utility compartment and is hinged along one edge for rotation away from the body of vehicle to allow ingress and egress. While the hinged edge is normally the bottom edge as in pick-up trucks, it may be hinged at the top as in dump trucks. In either case the tail gate normally swings outward for loading, unloading or dumping. Exceptions are shown in U.S. Pat. No. 1,764,615 where a member is allowed to swing inward and upward to promote removal of coal and U.S. Pat. No. 3,567,209 where a station wagon tail gate slides down into the body of the vehicle. While in usual vertical position, the tail gate of a moving pick-up truck is in the wake of the passenger compartment of the vehicle. Air passing over and around the passenger compartment turbulently flows into the utility compartment and is met by the vertical forward face of the tail gate creating significant air drag on the vehicle. While the drag on the tail gate is normally much less than that on the leading portion of the vehicle, it is significant and requires substantial additional force to move against the air friction. This fact has been recognized by vehicle users because of rising fuel costs.
Several attempts have been made to reduce air drag on tail gates in order to increase fuel efficiency, but all have resulted in undesired consequences. The first and most popular attempt has been to merely open the tail gate outward into a vertical cantilevered position, but this is dangerous to following drivers because the added length is not readily apparent and tail lights are often less visible. Additionally, leaving the tail gate sticking out is dangerous while manuvering the vehicle backward. A second attempt has been to completely remove the tail gate from the vehicle, but absence of the tail gate reduces the usefulness of the vehicle and is quite inconvenient to frequently replace. The third attempt has been to replace the conventional tail gate with one having numerous apertures such as that shown in U.S. Pat. No. 4,136,905 to allow air to pass through, but this attempt is also not completely successful because as aperture quantity and size increases hauling usefulness decreases, and as aperture quantity and size decreases air drag increases. Such open mesh tail gates reduce air drag a little but limit the vehicle to hauling material no smaller than the mesh openings.